Analysis of Ecological Change in Marine Ecosystems via Novel Imaging and Spectroscopic Techniques on Microalgae Cells

With the increase in anthropogenic pollutants such as: atmospheric CO₂ [carbon dioxide], fossil fuel combustion and fertilizer run off, the fate of the environment is of great importance. Through industrialization, the greenhouse gas, CO₂, is a major contributor to global warming; while nitrogen based fertilizer, causes the production of toxins due to harmful algal blooms. Both chemical impacts dissolve into marine ecosystems effecting the chemical composition of organisms such as microalgae. Microalgae remediate these changes by sequestering carbon and nitrogen; thus there is a need to understand how these impacts affect the ecosystem by detecting the change and relating it to its chemical source. It was demonstrated that microalgae respond sensitively to changes in their environment, the present dissertation expands the utilization of phytoplankton as an in-situ biological probe.

The goal of this dissertation is to develop analytical methodologies for investigations of chemical impacts on marine ecosystems via microalgae for examining the relationship between ambient chemical changes and microalgae remediation processes. Thus, experiments performed simulated the chemical shifts of selected chemical parameters. Impacts are measured by means of microscopic imaging and FT-IR spectroscopy for determining physical and chemical responses of microalgae. In order to quantitate these processes, novel chemometric algorithms were developed for determining ambient conditions based on imaging and spectroscopic data.

The first step to understanding these effects was developing an innovative image analysis technique to measure cell size and shape as a function of species and ambient conditions. This technique discriminated microalgae cells based on their physical parameters. For chemical analyses, FT-IR spectroscopy was used for detecting species chemically induced shifts in microalgae’s chemical composition. Within mixture species spectrum new chemical information was found and the suppression of chemical features was also revealed. Results demonstrated chemical change is present in the biomass and are nutrient source and concentration dependent. These novel analytical methodologies developed have demonstrated the ability to detect chemical changes under varying environmental conditions.